Lewis Short
nūbēcŭla (noun F) : dim.nubes
* A little cloud.
* Lit., Plin. 18, 35, 82, § 356.
* Transf., something cloudy or dark, a dark spot: mala urina, in quā veluti furfures atque nubeculae apparent,Plin. 28, 6, 19, § 68: smaragdi variā nubeculā improbati,id. 37, 5, 18, § 68: nubeculae et caligationes suffusionesque oculorum,id. 29, 6, 38, § 123; 20, 7, 26, § 61.
* Trop., a gloomy expression of countenance: frontis tuae nubecula,Cic. Pis. 9, 20.
Charlton T. Lewis, Charles Short, A Latin Dictionary